The geological conditions recorded by Eoarchean zircons and their included minerals

Abstract

We present the inclusion mineralogy, combine with morphology, texture and trace element geochemical data by the quantitative analysis of Eoarchean zircons, to show a case study in recording the characteristics of the Eoarchean felsic igneous zircons with known rock records. These can be a useful reference for detrital provenance studies by correlation. The Eoarchean zircons show a distinguish difference in inclusion assemblage compare to those in Hadean zircons with lesser quartz and muscovite content and more apatite and feldspar content. The rare of metamorphic minerals suggesting the Isua supracrustal belt had experienced limited low-grade metamorphism but the presence of secondary and hydrothermal minerals suggesting the alteration of included minerals. The rock types and post-crystallization alteration could be reflected on the zircon inclusion assemblages. The zircons morphological features and geochemistry characteristics indicating there were at least two types of magma source formed the Isua felsic rocks and the complicated crystallization environment in different locations on the Isua supracrustal belt. We examine the inclusion relationships and secondary features, suggesting the included minerals which would be primary or secondary, and the included minerals which would be sensitive to the surficial weathering and metasomatism. It may contribute to those Hadean studies in estimating the provenance’s primary chemical composition by zircon inclusion assemblage.